Coordinated and distributed collision reporting in cellular vehicle-to-everything (cv2x) networks

ABSTRACT

A method of wireless communication at a user equipment (UE) includes receiving a first collision report (s), each first collision report indicating at least one first monitored subset of sidelink resources that were monitored by a remote sidelink UE. The method also includes transmitting a second collision report indicating allocation collisions detected by the UE on a second monitored subset(s) of sidelink resources. Each of the second monitored subset(s) of sidelink resources differing from each of the first monitored subset(s) of sidelink resources indicated in the received first collision report(s). The second collision report further comprising an indication of each of the second monitored subset(s) of sidelink resources.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 17/103,799, filed on Nov. 24, 2020, and titled“CELLULAR VEHICLE-TO-EVERYTHING (CV2X) ALLOCATION COLLISION REPORTING,”the disclosure of which is expressly incorporated by reference herein inits entirety.

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wirelesscommunications, and more particularly to techniques and apparatuses forcoordinated and distributed collision reporting in cellularvehicle-to-everything (CV2X) networks.

BACKGROUND

Wireless communications systems are widely deployed to provide varioustelecommunications services such as telephony, video, data, messaging,and broadcasts. Typical wireless communications systems may employmultiple-access technologies capable of supporting communications withmultiple users by sharing available system resources. Examples of suchmultiple-access technologies include code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in varioustelecommunications standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunications standardis fifth generation (5G) new radio (NR). 5G NR is part of a continuousmobile broadband evolution promulgated by Third Generation PartnershipProject (3GPP) to meet new requirements associated with latency,reliability, security, scalability (e.g., with Internet of Things(IoT)), and other requirements. 5G NR includes services associated withenhanced mobile broadband (eMBB), massive machine type communications(mMTC), and ultra-reliable low latency communications (URLLC). Someaspects of 5G NR may be based on the fourth generation (4G) long termevolution (LTE) standard. There exists a need for further improvementsin 5G NR technology. These improvements may also be applicable to othermulti-access technologies and the telecommunications standards thatemploy these technologies.

Wireless communications systems may include or provide support forvarious types of communications systems, such as vehicle relatedcellular communications systems (e.g., cellular vehicle-to-everything(CV2X) communications systems). Vehicle related communications systemsmay be used by vehicles to increase safety and to help preventcollisions of vehicles. Information regarding inclement weather, nearbyaccidents, road conditions, and/or other information may be conveyed toa driver via the vehicle related communications system. In some cases,sidelink user equipments (UEs), such as vehicles, may communicatedirectly with each other using device-to-device (D2D) communicationsover a D2D wireless link. These communications can be referred to assidelink communications.

As the demands for sidelink communications increase in general, and CV2Xtechnology specifically penetrates the market and the number of carssupporting CV2X communication grows rapidly, the CV2X network isexpected to become increasingly crowded, especially for peak trafficscenarios. As a result, the chance of colliding allocations between UEsmay increase. An allocation collision may prevent successful decoding ofat least one of the colliding UE transmissions and in some cases mayprevent all of the colliding UE transmissions from being decoded. Forsafety reasons, there is a need to minimize the duration of repetitivecollisions between semi-persistently scheduled allocations of collidinguser equipments (UEs) or to minimize the number of future collisions ingeneral.

SUMMARY

In one aspect of the present disclosure, a method of wirelesscommunication by a user equipment (UE) includes receiving at least onefirst collision report, each first collision report indicating at leastone first monitored subset of sidelink resources that were monitored bya remote sidelink UE. The method further includes transmitting a secondcollision report indicating allocation collisions detected by the UE onat least one second monitored subset of sidelink resources, each of thesecond monitored subset(s) of sidelink resources differing from each ofthe first monitored subset(s) of sidelink resources indicated in thereceived first collision report(s). The second collision report furthercomprises an indication of each of the second monitored subset(s) ofsidelink resources.

Another aspect of the present disclosure is directed to an apparatus ofa user equipment (UE) for wireless communication, having a memory andone or more processors coupled to the memory. The processor(s) isconfigured to receive at least one first collision report, each firstcollision report indicating at least one first monitored subset ofsidelink resources that were monitored by a remote sidelink UE. Theprocessor(s) is further configured to transmit a second collision reportindicating allocation collisions detected by the UE on at least onesecond monitored subset of sidelink resources, each of the secondmonitored subset(s) of sidelink resources differing from each of thefirst monitored subset(s) of sidelink resources indicated in thereceived at least one first collision report. The second collisionreport further comprises an indication of each of the second monitoredsubset(s) of sidelink resources.

Another aspect of the present disclosure is directed to an apparatus forwireless communication including means for receiving at least one firstcollision report, each first collision report indicating at least onefirst monitored subset of sidelink resources that were monitored by aremote sidelink UE. The apparatus further includes means fortransmitting a second collision report indicating allocation collisionsdetected by the apparatus on at least one second monitored subset ofsidelink resources. Each of the second monitored subset(s) of sidelinkresources differing from each of the first monitored subset(s) ofsidelink resources indicated in the received first collision report(s),the second collision report further comprising an indication of each ofthe second monitored subset(s) of sidelink resources.

In another aspect of the present disclosure, a non-transitorycomputer-readable medium with program code recorded thereon isdisclosed. The program code is executed by a processor and includesprogram code to receive at least one first collision report, each firstcollision report indicating at least one first monitored subset ofsidelink resources that were monitored by a remote sidelink UE. Theprogram code further includes program code to transmit a secondcollision report indicating allocation collisions detected by the UE onat least one second monitored subset of sidelink resources, each of thesecond monitored subset(s) of sidelink resources differing from each ofthe first monitored subset(s) of sidelink resources indicated in thereceived first collision report(S). The second collision report furthercomprises an indication of each of the at least one second monitoredsubset of sidelink resources.

Aspects generally include a method, apparatus, system, computer programproduct, non-transitory computer-readable medium, user equipment, basestation, wireless communications device, and processing system assubstantially described with reference to and as illustrated by theaccompanying drawings and specification.

The foregoing has outlined rather broadly the features and technicaladvantages of examples according to the disclosure in order that thedetailed description that follows may be better understood. Additionalfeatures and advantages will be described. The conception and specificexamples disclosed may be readily utilized as a basis for modifying ordesigning other structures for carrying out the same purposes of thepresent disclosure. Such equivalent constructions do not depart from thescope of the appended claims. Characteristics of the concepts disclosed,both their organization and method of operation, together withassociated advantages will be better understood from the followingdescription when considered in connection with the accompanying figures.Each of the figures is provided for the purposes of illustration anddescription, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the above-recited features of the present disclosure can beunderstood in detail, a more particular description, briefly summarizedabove, may be had by reference to aspects, some of which are illustratedin the appended drawings. It is to be noted, however, that the appendeddrawings illustrate only certain typical aspects of this disclosure andare therefore not to be considered limiting of its scope, for thedescription may admit to other equally effective aspects. The samereference numbers in different drawings may identify the same or similarelements.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network.

FIGS. 2A, 2B, 2C, and 2D are diagrams illustrating examples of a firstfifth generation (5G) new radio (NR) frame, downlink (DL) channelswithin a 5G NR subframe, a second 5G NR frame, and uplink (UL) channelswithin a 5G NR subframe, respectively.

FIG. 3 is a diagram illustrating an example of a base station and userequipment (UE) in an access network.

FIG. 4 is a block diagram illustrating an example of avehicle-to-everything (V2X) system with a road side unit (RSU),according to aspects of the present disclosure

FIG. 5 is a graph illustrating a sidelink (SL) communications scheme, inaccordance with various aspects of the present disclosure.

FIG. 6 is a diagram illustrating collision scenarios, in accordance withaspects of the disclosure.

FIG. 7 is a graph illustrating a fully overlapping collision in a timeperiod, in accordance with aspects of the disclosure.

FIG. 8 is a flow diagram of collision measurement and reporting for asidelink receiving user equipment (UE), in accordance with aspects ofthe disclosure.

FIG. 9 is a call flow diagram illustrating collision detecting andreporting by a sidelink receiving user equipment (UE), in accordancewith aspects of the disclosure.

FIG. 10A is a diagram illustrating subsets of frequency resources forcollision monitoring, in accordance with various aspects of the presentdisclosure.

FIG. 10B is a diagram illustrating subsets of time resources forcollision monitoring, in accordance with various aspects of the presentdisclosure.

FIG. 11 is a timing diagram showing coordinated and distributedcollision reporting, in accordance with various aspects of the presentdisclosure.

FIG. 12 is a flow diagram of a method of wireless communication by auser equipment (UE), in accordance with aspects of the disclosure.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully below withreference to the accompanying drawings. This disclosure may, however, beembodied in many different forms and should not be construed as limitedto any specific structure or function presented throughout thisdisclosure. Rather, these aspects are provided so that this disclosurewill be thorough and complete, and will fully convey the scope of thedisclosure to those skilled in the art. Based on the teachings, oneskilled in the art should appreciate that the scope of the disclosure isintended to cover any aspect of the disclosure disclosed, whetherimplemented independently of or combined with any other aspect of thedisclosure. For example, an apparatus may be implemented or a method maybe practiced using any number of the aspects set forth. In addition, thescope of the disclosure is intended to cover such an apparatus ormethod, which is practiced using other structure, functionality, orstructure and functionality in addition to or other than the variousaspects of the disclosure set forth. It should be understood that anyaspect of the disclosure disclosed may be embodied by one or moreelements of a claim.

Several aspects of telecommunications systems will now be presented withreference to various apparatuses and techniques. These apparatuses andtechniques will be described in the following detailed description andillustrated in the accompanying drawings by various blocks, modules,components, circuits, steps, processes, algorithms, and/or the like(collectively referred to as “elements”). These elements may beimplemented using hardware, software, or combinations thereof. Whethersuch elements are implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem.

It should be noted that while aspects may be described using terminologycommonly associated with 5G and later wireless technologies, aspects ofthe present disclosure can be applied in other generation-basedcommunications systems, such as and including 3G and/or 4G technologies.

In cellular communications networks, wireless devices may generallycommunicate with each other via one or more network entities such as abase station or scheduling entity. Some networks may supportdevice-to-device (D2D) communications that enable discovery of, andcommunications with nearby devices using a direct link between devices(e.g., without passing through a base station, relay, or another node).D2D communications can enable mesh networks and device-to-network relayfunctionality. Some examples of D2D technology include Bluetoothpairing, Wi-Fi Direct, Miracast, and LTE-D. D2D communications may alsobe referred to as point-to-point (P2P) or sidelink communications.

D2D communications may be implemented using licensed or unlicensedbands. Additionally, D2D communications can avoid the overhead involvingthe routing to and from the base station. Therefore, D2D communicationscan improve throughput, reduce latency, and/or increase energyefficiency.

A type of D2D communications may include vehicle-to-everything (V2X)communications. V2X communications may assist autonomous vehicles incommunicating with each other. For example, autonomous vehicles mayinclude multiple sensors (e.g., light detection and ranging (LiDAR),radar, cameras, etc.). In most cases, the autonomous vehicle's sensorsare line of sight sensors. In contrast, V2X communications may allowautonomous vehicles to communicate with each other for non-line of sightsituations.

Sidelink (SL) communications refers to the communications among userequipment (UE) without tunneling through a base station (BS) and/or acore network. Sidelink communications can be communicated over aphysical sidelink control channel (PSCCH) and a physical sidelink sharedchannel (PSSCH). The PSCCH and PSSCH are similar to a physical downlinkcontrol channel (PDCCH) and a physical downlink shared channel (PDSCH)in downlink (DL) communications between a BS and a UE. For instance, thePSCCH may carry sidelink control information (SCI) and the PSCCH maycarry sidelink data (e.g., user data). Each PSCCH is associated with acorresponding PSSCH, where SCI in a PSCCH may carry reservation and/orscheduling information for sidelink data transmission in the associatedPSSCH. Use cases for sidelink communications may include, among others,vehicle-to-everything (V2X), industrial IoT (IIoT), and/or NR-lite.

A sidelink user equipment (UE) may detect allocations from othertransmitting UEs in sidelink channel resources. The UE may determine aquantity of detected allocations that collide with other detectedallocations, in each channel of the sidelink channel resources. Aspectsof the present disclosure provide for a UE to participate in a jointeffort for allocation collision monitoring and reporting.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) includes basestations 102, UEs 104, an evolved packet core (EPC) 160, and anothercore network 190 (e.g., a 5G core (5GC)). The base stations 102 mayinclude macrocells (high power cellular base station) and/or small cells102′ (low power cellular base station). The macrocells include basestations. The small cells 102′ include femtocells, picocells, andmicrocells.

The base stations 102 configured for 4G LTE (collectively referred to asevolved universal mobile telecommunications system (UMTS) terrestrialradio access network (E-UTRAN)) may interface with the EPC 160 throughbackhaul links 132 (e.g., S1 interface). The base stations 102configured for 5G NR (collectively referred to as next generation RAN(NG-RAN)) may interface with core network 190 through backhaul links184. In addition to other functions, the base stations 102 may performone or more of the following functions: transfer of user data, radiochannel ciphering and deciphering, integrity protection, headercompression, mobility control functions (e.g., handover, dualconnectivity), inter-cell interference coordination, connection setupand release, load balancing, distribution for non-access stratum (NAS)messages, NAS node selection, synchronization, radio access network(RAN) sharing, multimedia broadcast multicast service (MBMS), subscriberand equipment trace, RAN information management (RIM), paging,positioning, and delivery of warning messages. The base stations 102 maycommunicate directly or indirectly (e.g., through the EPC 160 or corenetwork 190) with each other over backhaul links 134 (e.g., X2interface). The backhaul links 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communications coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacrocells may be known as a heterogeneous network. A heterogeneousnetwork may also include home evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communications links 120 between the base stations 102 andthe UEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communications links 120 may use multiple-input andmultiple-output (MIMO) antenna technology, including spatialmultiplexing, beamforming, and/or transmit diversity. The communicationslinks may be through one or more carriers. The base stations 102/UEs 104may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc., MHz)bandwidth per carrier allocated in a carrier aggregation of up to atotal of Yx MHz (x component carriers) used for transmission in eachdirection. The carriers may or may not be adjacent to each other.Allocation of carriers may be asymmetric with respect to DL and UL(e.g., more or fewer carriers may be allocated for DL than for UL). Thecomponent carriers may include a primary component carrier and one ormore secondary component carriers. A primary component carrier may bereferred to as a primary cell (PCell) and a secondary component carriermay be referred to as a secondary cell (SCell).

Certain UEs 104 may communicate with each other using device-to-device(D2D) communications link 158. The D2D communications link 158 may usethe DL/UL WWAN spectrum. The D2D communications link 158 may use one ormore sidelink channels, such as a physical sidelink broadcast channel(PSBCH), a physical sidelink discovery channel (PSDCH), a physicalsidelink shared channel (PSSCH), and a physical sidelink control channel(PSCCH). D2D communications may be through a variety of wireless D2Dcommunications systems, such as FlashLinQ, WiMedia, Bluetooth, ZigBee,Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi accesspoint (AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunications links 154 in a 5 GHz unlicensed frequency spectrum. Whencommunicating in an unlicensed frequency spectrum, the STAs 152/AP 150may perform a clear channel assessment (CCA) prior to communicating inorder to determine whether the channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same 5 GHz unlicensedfrequency spectrum as used by the Wi-Fi AP 150. The small cell 102′,employing NR in an unlicensed frequency spectrum, may boost coverage toand/or increase capacity of the access network.

A base station 102, whether a small cell 102′ or a large cell (e.g.,macro base station), may include an eNB, gNodeB (gNB), or another typeof base station. Some base stations, such as gNB 180 may operate in atraditional sub 6 GHz spectrum, in millimeter wave (mmWave) frequencies,and/or near mmWave frequencies in communication with the UE 104. Whenthe gNB 180 operates in mmWave or near mmWave frequencies, the gNB 180may be referred to as an mmWave base station. Extremely high frequency(EHF) is part of the radio frequency (RF) in the electromagneticspectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between1 millimeter and 10 millimeters. Radio waves in the band may be referredto as a millimeter wave. Near mmWave may extend down to a frequency of 3GHz with a wavelength of 100 millimeters. The super high frequency (SHF)band extends between 3 GHz and 30 GHz, also referred to as centimeterwave. Communications using the mmWave/near mmWave radio frequency band(e.g., 3 GHz-300 GHz) has extremely high path loss and a short range.The mmWave base station 180 may utilize beamforming 182 with the UE 104to compensate for the extremely high path loss and short range.

The base station 180 may transmit a beamformed signal to the UE 104 inone or more transmit directions 182′. The UE 104 may receive thebeamformed signal from the base station 180 in one or more receivedirections 182″. The UE 104 may also transmit a beamformed signal to thebase station 180 in one or more transmit directions. The base station180 may receive the beamformed signal from the UE 104 in one or morereceive directions. The base station 180/UE 104 may perform beamtraining to determine the best receive and transmit directions for eachof the base station 180/UE 104. The transmit and receive directions forthe base station 180 may or may not be the same. The transmit andreceive directions for the UE 104 may or may not be the same.

The EPC 160 may include a mobility management entity (MME) 162, otherMMES 164, a serving gateway 166, a multimedia broadcast multicastservice (MBMS) gateway 168, a broadcast multicast service center (BM-SC)170, and a packet data network (PDN) gateway 172. The MME 162 may be incommunication with a home subscriber server (HSS) 174. The MME 162 isthe control node that processes the signaling between the UEs 104 andthe EPC 160. Generally, the MME 162 provides bearer and connectionmanagement. All user Internet protocol (IP) packets are transferredthrough the serving gateway 166, which itself is connected to the PDNgateway 172. The PDN gateway 172 provides UE IP address allocation aswell as other functions. The PDN gateway 172 and the BM-SC 170 areconnected to the IP services 176. The IP services 176 may include theInternet, an intranet, an IP multimedia subsystem (IMS), a PS streamingservice, and/or other IP services. The BM-SC 170 may provide functionsfor MBMS user service provisioning and delivery. The BM-SC 170 may serveas an entry point for content provider MBMS transmission, may be used toauthorize and initiate MBMS bearer services within a public land mobilenetwork (PLMN), and may be used to schedule MBMS transmissions. The MBMSgateway 168 may be used to distribute MBMS traffic to the base stations102 belonging to a multicast broadcast single frequency network (MBSFN)area broadcasting a particular service, and may be responsible forsession management (start/stop) and for collecting eMBMS relatedcharging information.

The core network 190 may include an access and mobility managementfunction (AMF) 192, other AMFs 193, a session management function (SMF)194, and a user plane function (UPF) 195. The AMF 192 may be incommunication with a unified data management (UDM) 196. The AMF 192 isthe control node that processes the signaling between the UEs 104 andthe core network 190. Generally, the AMF 192 provides quality of service(QoS) flow and session management. All user Internet protocol (IP)packets are transferred through the UPF 195. The UPF 195 provides UE IPaddress allocation as well as other functions. The UPF 195 is connectedto the IP services 197. The IP services 197 may include the Internet, anintranet, an IP multimedia subsystem (IMS), a PS streaming service,and/or other IP services.

The base station 102 may also be referred to as a gNB, Node B, evolvedNode B (eNB), an access point, a base transceiver station, a radio basestation, a radio transceiver, a transceiver function, a basic serviceset (BSS), an extended service set (ESS), a transmit and receive point(TRP), or some other suitable terminology. The base station 102 providesan access point to the EPC 160 or core network 190 for a UE 104.Examples of UEs 104 include a cellular phone, a smart phone, a sessioninitiation protocol (SIP) phone, a laptop, a personal digital assistant(PDA), a satellite radio, a global positioning system, a multimediadevice, a video device, a digital audio player (e.g., MP3 player), acamera, a game console, a tablet, a smart device, a wearable device, avehicle, an electric meter, a gas pump, a large or small kitchenappliance, a healthcare device, an implant, a sensor/actuator, adisplay, or any other similar functioning device. Some of the UEs 104may be referred to as IoT devices (e.g., a parking meter, gas pump,toaster, vehicles, heart monitor, etc.). The UE 104 may also be referredto as a station, a mobile station, a subscriber station, a mobile unit,a subscriber unit, a wireless unit, a remote unit, a mobile device, awireless device, a wireless communications device, a remote device, amobile subscriber station, an access terminal, a mobile terminal, awireless terminal, a remote terminal, a handset, a user agent, a mobileclient, a client, or some other suitable terminology.

Referring again to FIG. 1, in certain aspects, a receiving device, suchas the UE 104, may include an allocation collision detection module 198configured to receive at least one first collision report, each firstcollision report indicating at least one first monitored subset ofsidelink resources that were monitored by a remote sidelink UE. Theallocation collision detection module may also transmit a secondcollision report indicating allocation collisions detected by the UE onat least one second monitored subset of sidelink resources. Each of thesecond monitored subset(s) of sidelink resources differs from each ofthe first monitored subset(s) of sidelink resources indicated in thereceived first collision report(s), the second collision report furthercomprising an indication of each of the second monitored subset(s) ofsidelink resources.

Although the following description may be focused on 5G NR, it may beapplicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, andother wireless technologies.

FIG. 2A is a diagram 200 illustrating an example of a first subframewithin a 5G NR frame structure. FIG. 2B is a diagram 230 illustrating anexample of DL channels within a 5G NR subframe. FIG. 2C is a diagram 250illustrating an example of a second subframe within a 5G NR framestructure. FIG. 2D is a diagram 280 illustrating an example of ULchannels within a 5G NR subframe. The 5G NR frame structure may befrequency division duplex (FDD) in which for a particular set ofsubcarriers (carrier system bandwidth), subframes within the set ofsubcarriers are dedicated for either DL or UL, or may be time divisionduplex (TDD) in which for a particular set of subcarriers (carriersystem bandwidth), subframes within the set of subcarriers are dedicatedfor both DL and UL. In the examples provided by FIGS. 2A, 2C, the 5G NRframe structure is assumed to be TDD, with subframe 4 being configuredwith slot format 28 (with mostly DL), where D is DL, U is UL, and X isflexible for use between DL/UL, and subframe 3 being configured withslot format 34 (with mostly UL). While subframes 3, 4 are shown withslot formats 34, 28, respectively, any particular subframe may beconfigured with any of the various available slot formats 0-61. Slotformats 0, 1 are all DL, UL, respectively. Other slot formats 2-61include a mix of DL, UL, and flexible symbols. UEs are configured withthe slot format (dynamically through DL control information (DCI), orsemi-statically/statically through radio resource control (RRC)signaling) through a received slot format indicator (SFI). Note that thedescription infra applies also to a 5G NR frame structure that is TDD.

Other wireless communications technologies may have a different framestructure and/or different channels. A frame (10 ms) may be divided into10 equally sized subframes (1 ms). Each subframe may include one or moretime slots. Subframes may also include mini-slots, which may include 7,4, or 2 symbols. Each slot may include 7 or 14 symbols, depending on theslot configuration. For slot configuration 0, each slot may include 14symbols, and for slot configuration 1, each slot may include 7 symbols.The symbols on DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. Thesymbols on UL may be CP-OFDM symbols (for high throughput scenarios) ordiscrete Fourier transform (DFT) spread OFDM (DFT-S-OFDM) symbols (alsoreferred to as single carrier frequency-division multiple access(SC-FDMA) symbols) (for power limited scenarios; limited to a singlestream transmission). The number of slots within a subframe is based onthe slot configuration and the numerology. For slot configuration 0,different numerologies μ 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots,respectively, per subframe. For slot configuration 1, differentnumerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, persubframe. Accordingly, for slot configuration 0 and numerology μ, thereare 14 symbols/slot and 2μ slots/subframe. The subcarrier spacing andsymbol length/duration are a function of the numerology. The subcarrierspacing may be equal to 2{circumflex over ( )}μ*15 kHz, where μ is thenumerology 0 to 5. As such, the numerology μ=0 has a subcarrier spacingof 15 kHz and the numerology μ=5 has a subcarrier spacing of 480 kHz.The symbol length/duration is inversely related to the subcarrierspacing. FIGS. 2A-2D provide an example of slot configuration 0 with 14symbols per slot and numerology μ=0 with 1 slot per subframe. Thesubcarrier spacing is 15 kHz and symbol duration is approximately 66.7μs.

A resource grid may represent the frame structure. Each time slotincludes a resource block (RB) (also referred to as physical RBs (PRBs))that extends 12 consecutive subcarriers. The resource grid is dividedinto multiple resource elements (REs). The number of bits carried byeach RE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry reference (pilot)signals (RS) for the UE. The RS may include demodulation RS (DM-RS)(indicated as Rx for one particular configuration, where 100× is theport number, but other DM-RS configurations are possible) and channelstate information reference signals (CSI-RS) for channel estimation atthe UE. The RS may also include beam measurement RS (BRS), beamrefinement RS (BRRS), and phase tracking RS (PT-RS).

FIG. 2B illustrates an example of various DL channels within a subframeof a frame. The physical downlink control channel (PDCCH) carries DCIwithin one or more control channel elements (CCEs), each CCE includingnine RE groups (REGs), each REG including four consecutive REs in anOFDM symbol. A primary synchronization signal (PSS) may be within symbol2 of particular subframes of a frame. The PSS is used by a UE 104 todetermine subframe/symbol timing and a physical layer identity. Asecondary synchronization signal (SSS) may be within symbol 4 ofparticular subframes of a frame. The SSS is used by a UE to determine aphysical layer cell identity group number and radio frame timing. Basedon the physical layer identity and the physical layer cell identitygroup number, the UE can determine a physical cell identifier (PCI).Based on the PCI, the UE can determine the locations of theaforementioned DM-RS. The physical broadcast channel (PBCH), whichcarries a master information block (MIB), may be logically grouped withthe PSS and SSS to form a synchronization signal (SS)/PBCH block. TheMIB provides a number of RBs in the system bandwidth and a system framenumber (SFN). The physical downlink shared channel (PDSCH) carries userdata, broadcast system information not transmitted through the PBCH suchas system information blocks (SIBs), and paging messages.

As illustrated in FIG. 2C, some of the REs carry DM-RS (indicated as Rfor one particular configuration, but other DM-RS configurations arepossible) for channel estimation at the base station. The UE maytransmit DM-RS for the physical uplink control channel (PUCCH) and DM-RSfor the physical uplink shared channel (PUSCH). The PUSCH DM-RS may betransmitted in the first one or two symbols of the PUSCH. The PUCCHDM-RS may be transmitted in different configurations depending onwhether short or long PUCCHs are transmitted and depending on theparticular PUCCH format used. Although not shown, the UE may transmitsounding reference signals (SRS). The SRS may be used by a base stationfor channel quality estimation to enable frequency-dependent schedulingon the UL.

FIG. 2D illustrates an example of various UL channels within a subframeof a frame. The PUCCH may be located as indicated in one configuration.The PUCCH carries uplink control information (UCI), such as schedulingrequests, a channel quality indicator (CQI), a precoding matrixindicator (PMI), a rank indicator (RI), and hybrid automatic repeatrequest (HARD) acknowledgment/negative acknowledgment (ACK/NACK)feedback. The PUSCH carries data, and may additionally be used to carrya buffer status report (BSR), a power headroom report (PHR), and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with aUE 350 in an access network. In the DL, IP packets from the EPC 160 maybe provided to a controller/processor 375. The controller/processor 375implements layer 3 and layer 2 functionality. Layer 3 includes a radioresource control (RRC) layer, and layer 2 includes a service dataadaptation protocol (SDAP) layer, a packet data convergence protocol(PDCP) layer, a radio link control (RLC) layer, and a medium accesscontrol (MAC) layer. The controller/processor 375 provides RRC layerfunctionality associated with broadcasting of system information (e.g.,MIB, RRC connection control (e.g., RRC connection paging, RRC connectionestablishment, RRC connection modification, and RRC connection release),inter radio access technology (RAT) mobility, and measurementconfiguration for UE measurement reporting; PDCP layer functionalityassociated with header compression/decompression, security (ciphering,deciphering, integrity protection, integrity verification), and handoversupport functions; RLC layer functionality associated with the transferof upper layer packet data units (PDUs), error correction through ARQ,concatenation, segmentation, and reassembly of RLC service data units(SDUs), re-segmentation of RLC data PDUs, and reordering of RLC dataPDUs; and MAC layer functionality associated with mapping betweenlogical channels and transport channels, multiplexing of MAC SDUs ontotransport blocks (TBs), demultiplexing of MAC SDUs from TBs, schedulinginformation reporting, error correction through HARQ, priority handling,and logical channel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an inverse fastFourier transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to a differentantenna 320 via a separate transmitter 318TX. Each transmitter 318TX maymodulate an RF carrier with a respective spatial stream fortransmission.

At the UE 350, each receiver 354RX receives a signal through itsrespective antenna 352. Each receiver 354RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 356. The TX processor 368 and the RX processor 356implement layer 1 functionality associated with various signalprocessing functions. The RX processor 356 may perform spatialprocessing on the information to recover any spatial streams destinedfor the UE 350. If multiple spatial streams are destined for the UE 350,they may be combined by the RX processor 356 into a single OFDM symbolstream. The RX processor 356 then converts the OFDM symbol stream fromthe time-domain to the frequency domain using a fast Fourier transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 310. These soft decisions may be based on channelestimates computed by the channel estimator 358. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the base station 310 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 359, which implements layer 3 and layer 2functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the EPC 160. Thecontroller/processor 359 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the base station 310, the controller/processor 359provides RRC layer functionality associated with system information(e.g., MIB, SIBS) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the base station 310 may be used bythe TX processor 368 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 368 may be provided to different antenna352 via separate transmitters 354TX. Each transmitter 354TX may modulatean RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a mannersimilar to that described in connection with the receiver function atthe UE 350. Each receiver 318RX receives a signal through its respectiveantenna 320. Each receiver 318RX recovers information modulated onto anRF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the EPC 160. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

At least one of the TX processor 368, the RX processor 356, and thecontroller/processor 359 may be configured to perform aspects inconnection with the allocation collision detection module 198 of FIG. 1.In some aspects, the UE 104, 350 may include means for receiving, meansfor transmitting, means for monitoring, means for reporting, means forpreventing transmission, and means for selecting. Such means may includeone or more components of the UE 104, 350 described in connection withFIGS. 1 and 3.

FIG. 4 illustrates an example of a vehicle-to-everything (V2X) system500 with a road side unit (RSU), according to aspects of the presentdisclosure. As shown in FIG. 4, a V2X system 400 includes a transmitterUE 404 transmitting data to an RSU 410 and a receiving UE 402 viasidelink transmissions 412. Additionally, or alternatively, the RSU 410may transmit data to the transmitter UE 404 via a sidelink transmission412. The RSU 410 may forward data received from the transmitter UE 404to a cellular network (e.g., gNB) 408 via an UL transmission 414. ThegNB 408 may transmit the data received from the RSU 410 to other UEs 406via a DL transmission 416. The RSU 410 may be incorporated with trafficinfrastructure (e.g., traffic light, light pole, etc.) For example, asshown in FIG. 4, the RSU 410 is a traffic signal positioned at a side ofa road 420. Additionally or alternatively, RSUs 410 may be stand-aloneunits.

FIG. 5 is a graph illustrating a sidelink (SL) communications scheme inaccordance with various aspects of the present disclosure. The scheme500 may be employed by UEs such as the UEs 104 in a network such as thenetwork 100. In FIG. 5, the x-axis represents time and the y-axisrepresents frequency. The C2VX channels may be for 3GPP Release 16 andbeyond.

In the scheme 500, a shared radio frequency band 501 is partitioned intomultiple subchannels or frequency subbands 502 (shown as 502 _(s0), 502_(s1), 502 _(s2)) in frequency and multiple sidelink frames 504 (shownas 504 a, 504 b, 504 c, 504 d) in time for sidelink communications. Thefrequency band 501 may be at any suitable frequencies. The frequencyband 501 may have any suitable bandwidth (BW) and may be partitionedinto any suitable number of frequency subbands 502. The number offrequency subbands 502 can be dependent on the sidelink communicationsBW requirement.

Each sidelink frame 504 includes a sidelink resource 506 in eachfrequency subband 502. A legend 505 indicates the types of sidelinkchannels within a sidelink resource 506. In some instances, a frequencygap or guard band may be specified between adjacent frequency subbands502, for example, to mitigate adjacent band interference. The sidelinkresource 506 may have a substantially similar structure as an NRsidelink resource. For instance, the sidelink resource 506 may include anumber of subcarriers or RBs in frequency and a number of symbols intime. In some instances, the sidelink resource 506 may have a durationbetween about one millisecond (ms) to about 20 ms. Each sidelinkresource 506 may include a PSCCH 510 and a PSSCH 520. The PSCCH 510 andthe PSSCH 520 can be multiplexed in time and/or frequency. The PSCCH 510may be for part one of a control channel (CCH), with the second partarriving as a part of the shared channel allocation. In the example ofFIG. 5, for each sidelink resource 506, the PSCCH 510 is located duringthe beginning symbol(s) of the sidelink resource 506 and occupies aportion of a corresponding frequency subband 502, and the PSSCH 520occupies the remaining time-frequency resources in the sidelink resource506. In some instances, a sidelink resource 506 may also include aphysical sidelink feedback channel (PSFCH), for example, located duringthe ending symbol(s) of the sidelink resource 506. In general, a PSCCH510, a PSSCH 520, and/or a PSFCH may be multiplexed within a sidelinkresource 506.

The PSCCH 510 may carry SCI 560 and/or sidelink data. The sidelink datacan be of various forms and types depending on the sidelink application.For instance, when the sidelink application is a V2X application, thesidelink data may carry V2X data (e.g., vehicle location information,traveling speed and/or direction, vehicle sensing measurements, etc.).Alternatively, when the sidelink application is an IIoT application, thesidelink data may carry IIoT data (e.g., sensor measurements, devicemeasurements, temperature readings, etc.). The PSFCH can be used forcarrying feedback information, for example, HARQ ACK/NACK for sidelinkdata received in an earlier sidelink resource 506.

In an NR sidelink frame structure, the sidelink frames 504 in a resourcepool 508 may be contiguous in time. A sidelink UE (e.g., the UEs 104)may include, in SCI 560, a reservation for a sidelink resource 506 in alater sidelink frame 504. Thus, another sidelink UE (e.g., a UE in thesame NR-U sidelink system) may perform SCI sensing in the resource pool508 to determine whether a sidelink resource 506 is available oroccupied. For instance, if the sidelink UE detected SCI indicating areservation for a sidelink resource 506, the sidelink UE may refrainfrom transmitting in the reserved sidelink resource 506. If the sidelinkUE determines that there is no reservation detected for a sidelinkresource 506, the sidelink UE may transmit in the sidelink resource 506.As such, SCI sensing can assist a UE in identifying a target frequencysubband 502 to reserve for sidelink communications and to avoidintra-system collision with another sidelink UE in the NR sidelinksystem. In some aspects, the UE may be configured with a sensing windowfor SCI sensing or monitoring to reduce intra-system collision.

In some aspects, the sidelink UE may be configured with a frequencyhopping pattern. In this regard, the sidelink UE may hop from onefrequency subband 502 in one sidelink frame 504 to another frequencysubband 502 in another sidelink frame 504. In the illustrated example ofFIG. 5, during the sidelink frame 504 a, the sidelink UE transmits SCI560 in the sidelink resource 506 located in the frequency subband 502_(S2) to reserve a sidelink resource 506 in a next sidelink frame 504 blocated at the frequency subband 502 _(S1). Similarly, during thesidelink frame 504 b, the sidelink UE transmits SCI 562 in the sidelinkresource 506 located in the frequency subband 502 _(S1) to reserve asidelink resource 506 in a next sidelink frame 504 c located at thefrequency subband 502 _(S1). During the sidelink frame 504 c, thesidelink UE transmits SCI 564 in the sidelink resource 506 located inthe frequency subband 502 _(S1) to reserve a sidelink resource 506 in anext sidelink frame 504 d located at the frequency subband 502 _(s0).During the sidelink frame 504 d, the sidelink UE transmits SCI 568 inthe sidelink resource 506 located in the frequency subband 502 _(s0).The SCI 568 may reserve a sidelink resource 506 in a later sidelinkframe 504.

The SCI can also indicate scheduling information and/or a destinationidentifier (ID) identifying a target receiving sidelink UE for the nextsidelink resource 506. Thus, a sidelink UE may monitor SCI transmittedby other sidelink UEs. Upon detecting SCI in a sidelink resource 506,the sidelink UE may determine whether the sidelink UE is the targetreceiver based on the destination ID. If the sidelink UE is the targetreceiver, the sidelink UE may proceed to receive and decode the sidelinkdata indicated by the SCI. In some aspects, multiple sidelink UEs maysimultaneously communicate sidelink data in a sidelink frame 504 indifferent frequency subband (e.g., via frequency division multiplexing(FDM)). For instance, in the sidelink frame 504 b, one pair of sidelinkUEs may communicate sidelink data using a sidelink resource 506 in thefrequency subband 502 _(S2) while another pair of sidelink UEs maycommunicate sidelink data using a sidelink resource 506 in the frequencysubband 502 _(S1).

In some aspects, the scheme 500 is used for synchronous sidelinkcommunications. That is, the sidelink UEs may be synchronized in timeand are aligned in terms of symbol boundary, sidelink resource boundary(e.g., the starting time of sidelink frames 504). The sidelink UEs mayperform synchronization in a variety of forms, for example, based onsidelink SSBs received from a sidelink UE and/or NR-U SSBs received froma BS (e.g., the BSs 105 and/or 205) while in-coverage of the BS. In someaspects, the sidelink UE may be preconfigured with the resource pool 508in the frequency band 501, for example, while in coverage of a servingBS. The resource pool 508 may include sidelink resources 506. The BS canconfigure the sidelink UE with a resource pool configuration indicatingresources in the frequency band 501 and/or the subbands 502 and/ortiming information associated with the sidelink frames 504. In someaspects, the scheme 500 includes mode-2 RRA (e.g., supporting autonomousradio resource allocation (RRA) that can be used for out-of-coveragesidelink UEs or partial-coverage sidelink UEs).

Cellular vehicle-to-everything (C2VX) protocols enable vehicles tocommunicate and exchange messages or information with other vehicles,devices, and infrastructure. Vehicles or devices may exchangeinformation such as their location, speed, and direction with eachother. In addition, emergency and warning messages such as brakingalarms, red light warning, emergency braking, tunnel entry warning, androad work cautions, and similar messages may be transmitted. Thisinformation is shared on a certain minimum periodic basis and may beused to generate critical alerts to other vehicles, drivers, or devices.When necessary, infrastructure nodes help relay messages to vehicles atlonger distances. Vehicles or devices, such as UEs, select their ownresources for transmitting autonomously, that is, without direction froma network. The vehicle-to-vehicle communications incorporatingautonomous resource selection use the PC5 interface, which is based ondirect long-term evolution (LTE) sidelinks. In addition, UEs selecttransmission resources to satisfy latency, periodicity, and message sizerequirements.

Communication resources for both transmitting and receiving areallocated in subframes or slots. Transmission scheduling is autonomousand may be semi-persistent scheduling (SPS) or event driven scheduling.Event driven scheduling may be for alarm messages or one timetransmissions. In addition, event driven scheduling may also be used forany transmission with a lower latency requirement than SPS schedulingallows and may also be used for message sizes that do not fit SPSresources. The transmission scheduling may be based on CV2X resourcesensing procedures performed on received subframes. Sensing proceduresuse received signal strength indication (RSSI) measurements forcandidate Tx resource detection and may use received signal receivedpower (RSRP) measurements for candidate Tx resource exclusion. Resourcesmay be selected on a two-dimensional frequency versus time map withsubchannel grids in the frequency dimension and subframes in the timedimension. Autonomous resource selection refers to the selection of asubframe from the available subframes. Although the description ofresources is primarily with respect to subframes, other resources, suchas slots, are also contemplated.

For determining a candidate transmit resources list, a V2X device, suchas a UE, may identify a subset of twenty percent of the resources havingthe lowest resources energy (RSSI measurement). Each UE selectstransmission resources randomly from the candidate transmit resourceslist identified by each UE. The selected transmission resources may beused for any type of transmissions, such as semi-persistent scheduling(SPS) for a time duration that may last up to several seconds. There isa non-zero probability that two UEs will randomly select the sametransmission resources from the identified transmission resources listfor SPS transmission scheduling, which results in an allocationcollision on the selected transmission resources.

For SPS scheduling, monitoring of resource occupation and the timeduration of occupation may be indicative of resource usage for a longertime period. However, hidden UEs may affect the actual resource usage,which may differ from what is revealed by monitoring or sensingprocedures. With some SPS sessions lasting up to several seconds, hiddenUEs may not be visible for periods of time, preventing other UEs fromsensing the hidden UEs. This may lead to transmission scheduling onresources occupied by hidden UEs, which will result in allocationcollisions.

Colliding UEs may not be able to identify the collision and willcontinue to collide for the duration of the SPS time period, which maybe several seconds, before the colliding UEs reschedule their collidingtransmissions to other resources. To address long lasting allocationcollisions, the selection of transmission resources may use anallocation collision detection module 198, described above in connectionwith FIG. 1. The allocation collision detection module 198 helps toensure that UEs transmit and receive on vacant resources wheneverpossible and prevents or minimizes collisions and/or duration of thecollisions.

Before a UE transmits, the UE selects resources for the transmission.Ideally, the selected resources are vacant or at least include few orweak transmissions having lower priority messages. Autonomous resourceselection for transmitting on vacant resources includes power estimation(e.g., based on received signal strength indication (RSSI) measurements)to determine whether a resource is occupied. When determining candidateresources for transmission, a transmitting UE excludes unmeasuredsubframes due to previous transmissions, and also excludes resourcesbased on expected conflicts with other UEs.

Colliding UEs may not identify allocation collisions, as CV2X may be ahalf-duplex system. In a half-duplex communication system, atransmitting device does not receive on the same subframe. Thus, atransmitting device cannot measure the resources used for transmissionsby other UEs on the same transmission subframe. For every subframe, in ahalf-duplex communication system, the CV2X device may be in transmitmode or receive mode. Once a UE is in transmit mode, the UE cannotreceive on the transmit subframe. When this occurs, no sensingmeasurements are made on the subframe. Thus, colliding UEs in transmitmode on the subframe are unable to detect the colliding allocations fromeach other. Aspects of the present disclosure may assist in collisiondetection and reporting. In some aspects, the CV2X UEs within a CV2Xcoverage zone may jointly provide real time warnings of collisions bytransmitting indications of the monitored and detected collisions in acollision report or collision notification. The transmission of thecollision reports may utilize broadcasting, multicasting, or unicastingtechniques. The UEs within the CV2X coverage zone also monitor for thetransmitted collision reports and identify if a UE has any activelyscheduled transmission on the colliding resources indicated in thereport. A UE currently using resources indicated as colliding in thereceived report, will reschedule its transmissions to stop or reducecolliding for future transmissions.

Aspects of the present disclosure provide for reporting of collisionsobserved in a neighborhood (also referred to as coverage zone) by a UEover the corresponding monitored resources to help a transmitting UE onthe same resources to become aware of allocation collisions that may berelevant. On the subframes where a CV2X UE is in a reception mode, theUE monitors all of the control channels of the CV2X channel/band anddetects control channel (e.g., physical sidelink control channels(PSCCHs)) transmissions and shared channel allocations related to them(e.g., physical sidelink shared channels (PSSCHs)) transmitted from UEsin its neighborhood, (e.g., CV2X coverage area). The UEs in theneighborhood may also include infrastructure units, such as RSUs. Thecontrol channels and the associated shared channels may be transmittedwithin each CV2X resource defined by a subframe index in the timedimension and the CV2X subchannel index in the frequency dimension. ThePSSCH may occupy several subchannels. The UE determines presence ofcontrol channels in each control resource by attempting to demodulateand decode control channel hypotheses based on a demodulation referencesignal (DMRS) time cyclic shift or DMRS sequence hypothesis testing.

The strongest cyclic shift and DMRS sequence hypothesis per specificcontrol channel resource may be addressed for control channel decodingon the basis that there is a single control channel allocated on aspecific control channel resource. However, when a control channelallocation collision occurs, different colliding allocations may beassociated with a different control channel hypothesis, because the DMRScyclic shift (CS) and DMRS sequence option (in some cases, e.g., Release16 systems) are randomly selected by the transmitting UEs on eachtransmission occasion. Each control channel hypothesis may be detectedby successful decoding. Successful decoding of more than a singlecontrol channel (CCH) hypothesis on the same CCH resource may serve as abasis for collision detection on the addressed resource, or subchannel.The existence of multiple control channel allocations on the same CCHresource, which is an allocation collision, may also be detected withoutsuccessfully decoding all the colliding CCH allocations, based ondifferent CCH hypotheses. This may be performed in the domain of anestimated channel impulse response (CIR) based on the corresponding CIRand its aggregated energy metric obtained in each one of the cyclicshift ranges in the CIR response for every tested DMRS sequence option.The energy threshold is a metric for CIR energy estimated on acorresponding cyclic shift zone from the full CIR response. Anallocation collision may be determined where the CCH hypothesis energymetric crosses a threshold for several CCH hypotheses on the same CCHresource.

According to aspects of the present disclosure, the UE may detect anumber (or quantity) of detected control channel allocations on the samecontrol channel resource. The number may be based on whether a number ofcontrol channel hypotheses on the same resource are successfullydecoded, or whether a number of control channel hypotheses have anassociated CIR energy metric that is above a threshold value. Forexample, if the UE detects two control channel hypotheses with theestimated CIR energy values above the threshold value within aparticular control channel resource associated with a specific CV2Xsubchannel on a specific subframe, the UE determines two control signalsare present on the control resource and on the specific subchannel andspecific subframe. A CV2X channel may be a dispersive channel withmultiple paths (e.g., CIR taps). The CIR taps may be aggregated toproduce an energetic metric per hypothesis.

Collisions and overlaps may be caused by hidden UEs. A UE may be hiddendue to coverage. Thus, the hidden UE is not seen by some the CV2X UEsthat are in a reception mode, that is, monitoring CV2X resources, whilethe hidden UE may be in a transmission mode. Referring to FIG. 4, theRSU 410 may transmit data to the UE 404 via a sidelink transmission 412.The UE 402 may not be sensed by the RSU 410 because the UE 402 may betoo far from the RSU 410 or the corresponding channel between the twoUEs experiences severe shadowing. Hidden UEs will not exclude each otherwhen selecting resources and may therefore send colliding transmissionsif the UE selects the same transmission resource.

In addition, UEs may be hidden due to the half-duplex design of manyUEs. A half-duplex UE cannot transmit and receive at the same time. Whentransmitting, signals from the transmitting UE may collide with signalsfrom other transmitting UEs in the same coverage area because none ofthe colliding UEs can receive, sense, or detect signals from the otherUEs while transmitting. In effect, while transmitting, a UE is deaf toother UEs. Such collisions and overlaps are detrimental to cellularvehicle-to-everything (CV2X) communication.

Aspects of the present disclosure provide methods for reportingcollisions and overlaps by a CV2X UE (also referred to as a reportingUE). A UE may be any of the UEs 104, 402, 404, and 406 of FIGS. 1 and 4.According to aspects of the present disclosure, a UE that detectscollisions and overlaps may report the collisions and overlaps to aspecific transmitting UE involved in the detected collision (e.g.,unicast transmission) or to a group of transmitting UEs (e.g., multicasttransmission), or to all of the UEs in a CV2X coverage area (e.g.,broadcast transmission). The transmitting UE may select transmissiondifferent resources based on the reporting, improving the chances ofavoiding future collisions or overlaps.

FIG. 6 is a diagram illustrating collision scenarios, in accordance withaspects of the disclosure. FIG. 6 shows a cellular vehicle-to-everything(CV2X) resource map 600 in accordance with 3GPP Release 14 and Release15. The CV2X resource map 600 plots time on the horizontal axis andfrequency on the vertical axis. The time axis is divided into numberedsubframes from SF 0 through SF N. The frequency axis is divided intosubchannels, from subchannel 1 through subchannel M. Each subchannel hascontrol channel (CCH) resource blocks (RBs) and shared channel (SCH)(e.g., data) RBs.

FIG. 6 depicts three collision scenarios. A first collision scenario 602has full overlap between the allocations of UE 1 and UE 2 on both thecontrol channel and the shared channel in SF 0. A second collisionscenario 604 has a partial overlap between the UE 1 and the UE 2allocations with the CCH 1 and the SCH 1 of UE 1 overlapping with theSCH 2 of UE 2 in SF 2. A third collision scenario 606 is a time domaincollision, but not a frequency domain collision. A time domain onlycollision occurs when two UEs have transmissions on the same subframebut on different frequency resources (subchannels). The UEs in thisthird collision scenario 606 cannot receive transmitted messages fromeach other on this subframe because of the half-duplex transmission. Iftwo geographically close UEs are involved in the third type of collisionscenario, the UEs may be unable to prevent an accident between thembecause neither UE may receive at least some of the CV2X messages fromone another in time.

FIG. 7 is a diagram illustrating a fully overlapping collision in asubchannel and in a time period, (SF) in accordance with aspects of thedisclosure. That is, a control channel from UE1 collides with a controlchannel from UE2 in the same subchannel and the same SF or symbols.Control channel (CCH) collisions may be detected using multiplehypothesis decoding of the control channels. For 3GPP Releases 14 and15, control channel transmission may be performed using a constantdemodulation reference signal (DMRS) sequence and with a randomlyselected cyclic shift (CS), by each UE, in time for each transmission.This cyclic shift may be randomly selected from several pre-definedcyclic shift options. This CS selection allows differentiation betweencolliding CCHs in the time domain (TD) based on an observed channelimpulse response (CIR).

The cyclic shift may be randomly selected among four values thatseparate the symbol time range into four non-overlapping subzones. Thesubzones are shown in FIG. 7 with the cyclic shift (CS) identifiers CSidx 1 (index 1) range, CS idx 2 (index 2) range, CS idx 3 (index 3)range, and CS idx 4 (index 4) range. The four non-overlapping subzonesCS idx 1 range, CS idx 2 range, CS idx 3 range, and CS idx 4 range makethe control channels with different cyclic shift nearly orthogonal interms of the time domain, as shown in FIG. 7. Thus, the signal receivedin the CS idx 3 range is detectable, as is the signal received in the CSidx 4 range, even though they both are in the same symbol. In otherwords, although the two transmissions arrive in the same symbol, becauseof the cyclic shift offset, the signals can be distinguished from oneanother. Thus, a UE may detect the collision between the control channelallocation arriving in the CS idx 3 range with a maximum CIR tap peak atapproximately the CIR taps 76-77 and the control channel arriving in theCS idx 4 range with a maximum CIR tap peak at approximately the CIR tap108. Each CS hypothesis may be represented by the CIR energy metricdetermined from the corresponding CS CIR response subzone.

In some cases, however, two transmissions may have the same cyclicshift. In these cases, the two control channel transmissions are notorthogonal. As a result, only the strongest signal will be decoded.Thus, some of the colliding control channel allocation may not bedecodable if those colliding control channels are transmitted with aDMRS having the same CS configuration. If this occurs, it may not bepossible to identify the collision from a single scheduling occurrence,in contrast to when transmissions use different cyclic shifts, enablingidentification of the colliding control channels in a single schedulingoccurrence.

Aspects of the present disclosure are directed to identifying collisionsbetween control channels, even when colliding control channeltransmissions have the same cyclic shift on some of the transmissionoccurrences, by observing multiple control channel transmissionoccurrences of the same SPS scheduling. If two control channels collidethen the shared channels automatically collide. An overlap between theshared channels may vary because the two colliding control channels maysignal (e.g., the associated PSSCH) a different shared channelallocations size. Every subsequent transmission of the same SPSscheduling may use a different cyclic shift randomly selected by atransmitting UE for each transmission. Thus, the combination of cyclicshifts for colliding control channels varies for each transmission.Because the collisions targeted for identification use SPS, everysubsequent scheduling occurrence may provide a new opportunity to detectthe collision. After four subsequent transmissions of the same SPS, theprobability of detecting a collision is nearly one, as shown in Table 1,below. Increasing the number of trials to detect a collision between twoSPS streams increases the probability of detection according to theformula below (applicable to Release 14 and Release 15 CV2X UEs):

P_(det)(n) = 1 − (4/16)^(n),

where n is a number of observation subframes with the same collidingcontrol channel allocations.

The detection time and detection probabilities are shown in Table 1,below for up to four transmission occurrences of the same SPS (alsoreferred to as observation subframes).

TABLE 1 n P_(det)(n) Detection Time 1 0.75 SPS_period  2 0.9375SPS_period*2 3 0.9844 SPS_period*3 4 0.9961 SPS_period*4

For 3GPP Release 16 and beyond, different orthogonal control channelhypotheses for a control channel may use a combination of differentcyclic shifts, as described above and different demodulation referencesignal (DMRS) sequences. To detect control channel collisions forRelease 16 and beyond, control channel hypotheses based on both cyclicshift and DMRS sequences should be decoded.

According to aspects of the present disclosure, a UE may also detectcollisions between a shared channel and a control channel, as seen inthe second collision scenario 604 of FIG. 6. A shared channeltransmission may be performed with a demodulation reference signal(DMRS) different from the control channel DMRS, and thus collisiondetection between the control channel and the shared channel isdifferent. The shared channel to control channel collision may beidentified by decoding sidelink control information fields from bothconflicting transmissions. Based on the sidelink control information,the UE may determine where a shared channel is expected. For example,the UE may build a mapping of the corresponding shared channel locationsknown from the resource indication value (RIV) fields of thecorresponding decoded sidelink control information.

In this situation described above, both control channels are assumed tobe decodable. A control channel may be decodable even with a negativesignal-to-noise ratio (SNR) that is above a sensitivity threshold. Ifthe CCH SNR is below the sensitivity threshold because of an overlapwith a strong CCH, then the CIR taps may also be below the value of theinterference added to the noise floor. As a result, the taps may not bedetectable based on the energy metric. Each allocation in Release 14 andRelease 15 may be transmitted using transmissions and retransmissions.Each transmission and retransmission has a corresponding CCH having aresource indication value (RIV) field. The RIV field providesinformation on the SCH mapping of transmissions and retransmissions. TheRIV may be redundant because decoding one of the two CCHs related to thesame allocation may also yield the mapping information. Any two of theCCHs may be addressed in general for collision detection, with one CCHproviding information for the current SCH and the other providinginformation for the retransmissions SCH up to fifteen subframes later.The second CCH provides information on the transmissions andretransmissions up to fifteen subframes earlier. The transmission andretransmission may have a gap of up to fifteen subframes.

According to aspects of the present disclosure, after the collisionshave been detected and mapped, the collision map may be pruned beforetransmitting a collision report. For example, some collisions may beintentional and introduced by transmission scheduling algorithms forhigher priority messages in highly congested scenarios, and thus, shouldbe allowed to exist. A higher priority message may be an emergencymessage, for example. Some CV2X resources having relatively low powermay be classified as available for scheduling higher priority messages,depending on the CV2X channel busy ratio (CBR). Due to the low energy onthese resources, the high priority messages may still be decodable eventhough a collision occurs, such as when there is intentional overwritingby the transmission scheduling algorithm. That is, the interferingenergy on the lower power resources may not prevent decoding ofscheduled higher priority transmissions by the nearest UE. Suchintentional collisions may be excluded from the collision report.

According to aspects of the present disclosure, identified collisionsare analyzed subject to a congestion scenario and may be pruned if thecollisions align with a congestion scheduling policy. The congestionscheduling policy may be based on a channel busy ratio (CBR), which isdefined as the portion of a subchannel (measured by a sensing procedure)over a sensing period duration with an RSSI measured above a pre-definedthreshold.

According to aspects of the present disclosure, pruning intentionalcollisions from the collision report may begin with attempting to decodethe sidelink control information for each of the transmissions involvedin an allocation collision. Then, the UE may measure the controlchannel/shared channel (CCH/SCH) received signal received power (RSRP)for the decoded channels. The colliding allocations are then sorted inincreasing order based on the RSRPs. The UE measures RSRP differencesand priority differences, with priority information conveyed by thecontrol message, of the colliding allocations in accordance withformulas (1) and (2) below:

$\begin{matrix}{\Delta_{RSRP} = {{RSRP_{2}} - {RSRP_{1}}}} & (1) \\{\Delta_{Priority} = {{{Priority}\mspace{14mu}\left( {SCI}_{2} \right)} - {{Priortiy}\mspace{14mu}\left( {SCI}_{1} \right)}}} & (2)\end{matrix}$

where Δ_(RSRP) represents the RSRP difference, RSRP1 and RSRP2 are RSRPsfor the first and second transmissions, Δ_(Priority) is the prioritydifference, and Priority (SCI₂) and Priority (SCI₁) are messagepriorities for the first and second transmissions.

Once the measuring is completed, the pruning criteria, given in formula(3) below, is applied so that collisions with an RSRP difference lessthan a threshold (THR) are not pruned.

$\begin{matrix}{\Delta_{RSRP} < {{THR}\left( {\Delta_{Priority},{CBR}} \right)}} & (3)\end{matrix}$

where THR (Δ_(Priority), CBR) is a threshold that is a function of thepriority difference and how busy the channel is (channel busy ratio(CBR)).

According to aspects of the present disclosure, sidelink informationfrom the application level that provides the associated UE locations mayalso be used for more efficient allocation collision pruning. Thissidelink information may be useful in cases where the instantaneous RSRPmeasurement may be misleading. This approach may also aid in pruningtime domain only collisions.

After pruning, the UE may build the collision report. The collisionreport may include a list of resources where collisions were detected.The collision report may be in the form of a two-dimensional bit mapwhere each bit corresponds to the CV2X resources from thetwo-dimensional resource map, (e.g., subchannel, subframe). Each bit maybe set to one in case of the event of a collision on the correspondingresource. In some aspects, each resource may be described by itsfrequency subchannel as well as its subframe index. In other aspects,the report may also include a description of the subset of resourcesover which collision measurements were performed by the reporting UE.

Once the collision report has been built, it is transmitted to the UEsin the coverage zone. The collision report may be broadcast to the UEs,but may also be multicast or unicast, for example, with Release 16 andlater UEs. When the collision report is transmitted using multicast andunicast, the collision report may be transmitted to a specific group ofUEs, or to a particular UE. A further aspect may provide a collisionnotification for a specific UE with a description of the resources wherethe specific UE has a transmission involved in the identifiedcollisions. Selecting the group of UEs or particular UE may be based onthe UEs involved in the detected collision. Transmitting the collisionreport using multicast or unicast may rely on a field in the controlchannel that identifies each UE and allows association of each collidingallocation to specific UEs based on the control channel decoding.

According to aspects of the present disclosure, the collision report maybe sent as a data message on the application layer or may be sent on thephysical (PHY) layer depending on a deployment scenario. The PHY layermay have a defined reporting procedure as part of the PHY layerprocedures definitions. For example, when a combination of Release 14,15, 16 or later UEs are deployed, the UEs may report collisions based onRelease 16 or higher PHY layer definitions and may use the correspondingreporting framework in accordance with a collision reporting definitionspecified by 3GPP. When only Release 14 and 15 UEs are deployed, the UEsmay transmit the collision report as a data message of the applicationlayer. For example, the UEs may send the collision report as datapackets in the CV2X safety application level. The data message formatmay be either proprietary or standardized. In a deployment scenarioincluding Release 14, 15, 16 and later UEs, as well as wide area network(WAN) LTE or new radio (NR) UEs, the UEs may transmit the report via WANon either the application layer or the PHY layer. For PHY layerreporting option, specification definitions for the WAN PHY layer mayintroduce a new report type dedicated for CV2X collision reporting.

Once the collision report has been transmitted to the UEs, each UEmonitors the collision report and determines if any of the resourcesused for the UE's active scheduled transmissions are included in thecollision report. If the UE's scheduled transmission resources areincluded in the collision report, the UE triggers reschedulingprocedures to stop colliding on the SPS transmission resources or toavoid collisions for a reserved retransmission resource, or for any typeof scheduled future transmission. A reserved retransmission resource isa conditionally scheduled resource for 3GPP Release 16 and beyondsystems. As an example, for a CV2X configuration where a UE has a singleSPS transmission session within 100 msec, collisions may be stopped in400 milliseconds or less once rescheduling occurs. In many cases, thecollisions may be stopped within 100 milliseconds if the collisions aredetected after a single transmission occurrence of the collidingallocations.

Based on the collision reports received, a transmitting UE may select orreselect a transmit resource subchannel and subframe, according to thecollision information. Reselection may include dropping an existingsemi-persistent schedule (SPS) and beginning a new SPS.

Multiple UEs reporting collisions based on the monitoring of the sameresources results in multiple duplicative collision reports. Theduplicative collision reports may have identical content and needlesslywaste channel capacity.

To support collision reporting for the CV2X band, a UE may havesignificantly increased processing requirements because of the need todecode multiple control channel hypotheses on every CV2X subchannel andon every received subframe. A CV2X UE may address the strongest CCHhypothesis detected on each subchannel and subframe. Aspects of thedisclosure provide distributed processing mechanisms to ease theadditional processing for a specific UE in support of allocationcollision reporting.

In one aspect, collision reporting may be defined as a capability, or asa best effort if following a proprietary framework. To reduce anexpected increase in processing requirements, the pool of CV2X resourcesmay be subdivided into subsets in relation to allocation collisionreporting. Some subsets may include a fraction of subframes in timeand/or some subsets may include a fraction of subchannels in frequency.Based on the UE capability (or best efforts indication), a limitednumber of subsets may be opportunistically addressed by a UE formonitoring for collision reporting over the reduced number of resourcesubsets. Each collision report may provide a description of the resourcesubset(s) that were measured.

In another aspect of the present disclosure, each UE monitors receivedcollision reports and identifies resource subsets not covered by thereporting. In this aspect, each UE may select collision measurementresources from the non-covered resource subsets.

According to these aspects of the present disclosure, collisionreporting coverage may be provided with a jointly distributed effort bythe UEs within a coverage zone. This distributed effort ensures thatadditional processing requirements are reasonable and limited. Moreover,in some aspects, only a limited number of more capable UEs monitor forand report collisions. These more capable UEs may be infrastructureunits, for example. An additional advantage of the distributed effort isthat “flooding” of the CV2X channels by transmissions of numerouscollision reports covering the same collision events, may be avoided orreduced to a negligible level.

An aspect of the disclosure allows collision detection to be performedwith some latency. In other words, real time processing may not benecessary. The reasonable latency that is not expected to affect overallcollision mitigation delay may be within the SPS period boundaries andmay mitigate instant processing of peak loads.

A further aspect of the disclosure provides that collision reporttransmission may be collision event driven. Alternatively, the collisionreport transmission may occur in a selected time period, such as onceper minimum time period with no collision indication but with adescription of the monitored resources subset.

FIG. 8 is a flow diagram of collision measurement and reporting for asidelink receiving user equipment (UE), in accordance with aspects ofthe disclosure. A method 800 begins with cellular vehicle-to-everything(CV2X) subframes (Rx SFs) received by the sidelink UE. The sidelink UEmay be the UE 104, 402, 404, and 406 of FIGS. 1 and 4. The receivedsubframes are input to a UE, specifically, the collision detectionmodule 198 of FIG. 1. In block 802, the UE identifies collisions on theselected CV2X resources subset based on a UE processing capability, aswell as multiple control channel (CCH) hypothesis decoding, and resourceindication value (MV) field analysis. In parallel with identifyingcollisions at block 802, in block 804, the UE continuously monitorstransmitted collision reports. If any CV2X resources subsets areidentified in the collision reports, then, in block 806 the UEidentifies CV2X resource subsets not covered by the collision reports.The CV2X resource subsets not covered by the collision reports are inputto block 802, which is described above.

From block 802, the identified collisions are input to block 808, wherethe UE prunes identified collisions. The UE prunes the collisions toremove collisions that may be aligned with a scheduling policy, forexample, intentional collisions that may take place in a congested CV2Xchannel scenario are pruned. The pruning may be CBR dependent. Thecollisions to be reported and resource subsets addressed by thecollision detection are input to block 810, where the UE builds thecollision report. At block 812, the UE initiates collision reporttransmission. The collision report is then transmitted on CV2Xtransmission subframes (Tx SFs) as a CV2X collision report.

From block 804, the UE also identifies resources included in thecollision reports. In block 814, the UE may check if any currentsemi-persistent schedule (SPS) transmissions, or any other type offuture scheduled transmissions or allocations use resources listed inthe collision report. If no resources used by the UE are included in thecollision report, processing returns to block 804 and the UE continuesto monitor transmitted collision reports. If the UE does assign for SPStransmission (or any other scheduled transmission) any resources listedin the collision report, the process moves to block 816. At block 816,the UE triggers a rescheduling procedure for SPS transmission, or anyother transmission involved in the collisions indicated in the receivedcollision report. In other words, the sidelink transmitting UEreschedules its transmissions based on the collision report. Therescheduling may be based on the UE sensing procedures.

FIG. 9 is a call flow diagram illustrating collision detecting andreporting by a sidelink receiving user equipment (UE), in accordancewith aspects of the disclosure. The call flow begins with multiple UEs,such as UE 2-UE n transmitting collision reports on cellularvehicle-to-everything (CV2X) subframes (SFs), at time T1, to UE 1. Attime T2, UE 1, which is monitoring for transmitted collision reports,identifies the indicated CV2X resources with colliding allocations fromthe collision report. The sidelink UE receiving the collision report maybe the UE 104, 402, 404, and 406 of FIGS. 1 and 4. UE 1 also identifiesCV2X resources not covered in the collision report at time T3. UE 1 thenidentifies collisions on selected CV2X resources at time T4. At time T5,UE 1 prunes the detected collisions in the collision report anddetermines the collisions to be reported. At time T6, UE 1 determineswhich resources subset is addressed in the collision detection. Then, attime T7, UE 1 begins building the collision report. At time T8, UE 1includes resources addressed in the allocation collision detection. Thebuilding of the collision report is completed by time T9. Alternatively,at time T9, UE 1 checks the next received collision report as itcontinues to monitor for received collision reports at time T10. Ifnecessary, UE 1 triggers rescheduling for its SPS transmissions or anyother scheduled transmissions at time T11. At time T12, UE 1 transmitsthe collision report to UE 2 through UE n as a CV2X collision report.

As described above, UEs and RSUs may perform collision reporting in aCV2X network. Given that colliding UEs cannot identify collisions bythemselves, other UEs and RSUs (not transmitting in the resources wherecollisions takes place) assist in detection of these collisions. AllUEs, including the colliding UEs, may monitor collision reports andidentify if they are involved in the reported collisions. The UEs mayrespond by rescheduling semi-persistently scheduled (SPS) transmissionsto prevent future collisions.

Aspects of the present disclosure define a framework of distributedcollision detection and reporting as a joint effort of CV2X network UEsand RSUs to mitigate long lasting SPS allocation collisions. Decodingmultiple control channel hypotheses on every CV2X subchannel and onevery received subframe significantly increases the CV2X UE processingrequirements. It may be desirable to limit the processing complexity ordynamically adjust the processing complexity depending on a UE'scapability. Aspects of the present disclosure introduce a coordinationmechanism that prevents duplication of collision reporting for the samecollision events detected by multiple UEs. These aspects prevent anexcessive number of reports from flooding the network. Aspects of thepresent disclosure address the lack of a centralized scheduling entityin a CV2X network with PC5 interfaces, and also the autonomousscheduling that occurs in a CV2X network. The techniques of the presentdisclosure limit extra processing involved with allocation collisionmonitoring and reporting, and also prevent creation and transmission ofredundant reports.

According to aspects of the present disclosure, coordinated anddistributed collision reporting is performed only by capable UEs.Whether a UE is considered capable may be based on the hardware of theUE. Each capable UE addresses only a partial subset of time andfrequency resources for collision detection and reporting, thus limitingcomplexity. Each UE selects a range of resources to monitor andadvertises the range to all the other UEs to avoid report duplication.By monitoring different subsets of resources with different UEs,complete coverage may be achieved for collision reporting with a jointlydistributed effort by all the UEs, while reducing processingrequirements. This result can be achieved using even a limited number ofcapable UEs. The techniques of the present disclosure prevent duplicatereports from multiple UEs that may respond to the same collision event.These novel techniques may be standards-based or a proprietary CV2Ximplementation.

According to aspects of the present disclosure, collision reporting maybe defined as a capability, or alternatively, as a best effort iffollowing a proprietary framework. Each capable UE will contribute to ajoint effort of allocation collision monitoring and reporting in a CV2Xnetwork. Alternatively, or additionally, allocation collision monitoringand reporting may be performed by infrastructure units (e.g., RSUs) thatare less sensitive to complexity requirements.

According to aspects of the present disclosure, an entire pool of CV2Xresources may be subdivided into subsets. A subset may include somefraction of subframes in time and/or some fraction of subchannels infrequency. The subsets may include continuous or discontinuousresources. The subset may include discontinuous resources, for example,when certain subchannels are excluded due to the resource pooldefinition. A UE may monitor one or more of these subsets. The UEmonitors a subset(s) that is different from any subset monitored byother UEs or RSUs during a predetermined time period.

FIG. 10A is a diagram illustrating subsets of frequency resources forcollision monitoring, in accordance with various aspects of the presentdisclosure. FIG. 10A shows three subsets of CV2X resources for collisionmonitoring and reporting, with frequency-based partitioning of theresources. Each subset occupies a number of consecutive CV2Xsubchannels, in this example. All subframes (SFs) within a sensingperiod are included in each subset. FIG. 10A shows the subframe indexes(idx) SF0-SFN within the sensing period boundaries. A first subset 1002includes subchannel 1 and subchannel 2. A second subset 1004 includessubchannel 3 and subchannel 4. A third subset 1006 includes subchannelM−1 and subchannel M.

FIG. 10B is a diagram illustrating subsets of time resources forcollision monitoring, in accordance with various aspects of the presentdisclosure. FIG. 10B shows three subsets of CV2X resources for collisionmonitoring and reporting, with time-based partitioning of the resources.Each subset spans the entire range of CV2X subchannels but only some SFindexes are included in each subset. FIG. 10B shows the subframe indexesSF0-SFN within the sensing period boundaries. A first subset 1008includes subframes 0, 3, . . . N−5, and N−2. A second subset 1010includes subframes 1, 4, . . . N−4, and N−1. A third subset 1012includes subframes 2, 5, . . . N−3, and N. Report processing may occurbetween subframes included in a given subset. For example, with thefirst subset 1008, the UE may monitor SF0 for allocation collisions,perform the processing during SF1 and SF2, and monitor again at SF3.

In another aspect of the present disclosure, UE capability (or anopportunistic limitation) defines the number of subsets that can bemonitored by a UE for collisions detection and reporting. The UEcapability keeps a processing envelope below a processing threshold. TheUE capability may be transmitted in the collision report. Each collisionreport may also provide a description/indication of the resourcesubset(s) that was monitored by the UE.

In another aspect of the present disclosure, each UE may monitorcollision reports received from other UEs and RSUs, and identifyresources that are not covered by the distributed collision reportingresources (subsets). The UE monitors for allocation collisions onresources that were not monitored by the other UEs and RSUs, in otherwords, the non-covered resource subsets. Thus, multiple UEs may jointlymonitor all resources.

In another aspect of the present disclosure, this resources selectionprocess occurs dynamically and adaptively. If several capable UEs selectthe same resource subset(s) for collisions monitoring, they are notlikely to transmit the collision report on the same subframe (at thesame time). This is assuming that collision report transmission will bebased on event driven scheduling and not semi persistent scheduling.Thus, this kind of collision may occur one time, but not along severalconsecutive transmissions of collision report by these UEs.Consequently, assuming that each one of the UEs that selected the sameresource subset for allocation collision monitoring and reporting willbe able to receive a collision report transmitted by the other UE, oneof the UEs drops the transmission of the prepared report at the momentit receives from another UE (or RSU) a collision report for the samesubset of resources. Resource subset reselection for collisionmonitoring and reporting may be triggered accordingly. The reselectionexcludes all resources monitored by other UEs and RSUs. In case ofpartial overlapping of the monitored resources, the portion of thereport corresponding to the overlapping resources will be dropped fromthe transmission. The portion of the report corresponding to thenon-overlapping resources is preserved. In some aspects, the UErecomposes the report in response to the partial overlap.

According to further aspects of the present disclosure, the collisionreport transmission may be a collision event driven. In other aspects, areport will be transmitted at least once every predetermined time periodT (e.g., every T seconds) even when no collisions are detected.Similarly, a UE receives a report at least once every predetermined timeperiod T. This concept may be referred to as “keep alive.” In case of nodetected collisions during the time period T, the collision report maybe transmitted without collision indication fields. Rather, thecollision report may be transmitted with a description of the monitoredresources subset. The description of the monitored resources subsetkeeps other UEs synchronized on resource coverage for collisionmonitoring and reporting in the network. The minimum reportingperiodicity T may be included in the report, for example, when nocentralized entity instructs UEs for determining the time period T. Thetime period T allows UEs to know how long to wait before assumingcorresponding resources are not monitored by another UE. In someaspects, all or some of the UEs indicate the time period T in theirreport. Although a ‘periodicity’ is described, it is noted thatcollision reporting may be event driven, in which case the ‘periodic’transmission may not occur at the same subframe every period.

The processing involved for collision detection may not necessarilyoccur in real time. The processing may permit some latency within SPStransmission period boundaries. This relaxed specification may mitigateinstant peak load and also motivates a resource subdivision into subsetson the time axis for collisions monitoring.

FIG. 11 is a timing diagram showing coordinated and distributedcollision reporting, in accordance with various aspects of the presentdisclosure. At time t1, a first UE, UE1, receives a collision reportfrom a second UE, UE2. The collision report indicates any allocationcollisions detected by the second UE, UE2, as well as the resources thesecond UE, UE2, monitored. At time t2, the first UE, UE1, receives acollision report from a third UE, UE3. This collision report indicatesany allocation collisions detected by the third UE, UE3, as well as theresources the third UE, UE3, monitored.

At time t3, the first UE, UE1, determines which resources have beenmonitored by the other UEs, UE2, UE3. Based on which resources weremonitored by the second and third UEs, UE2, UE3, the first UE, UE1,determines a subset of resources to monitor. The subset includesresources that were not monitored by the other UEs, UE2, UE3. At timet4, the first UE, UE1, monitors the determined subset of resources forallocation collisions. At time t5, the first UE, UE1, transmits acollision report to the other UEs, UE2, UE3, indicating any detectedallocation collisions. The collision report also indicates the subset ofresources the first UE, UE1, monitored.

As indicated above FIGS. 6-11 are provided as examples. Other examplesmay differ from what is described with respect to FIGS. 6-11.

FIG. 12 is a flow diagram of a method 1200 of wireless communication bya sidelink user equipment (UE), in accordance with aspects of thedisclosure. The example process 1200 is an example of coordinated anddistributed collision reporting in cellular vehicle-to-everything (CV2X)networks. The operations of the process 1200 may be implemented by a UE350.

At block 1202, the UE receives at least one first collision report, eachfirst collision report indicating at least one first monitored subset ofsidelink resources that were monitored by a remote sidelink UE. Forexample, the UE (e.g., using the antenna 352, demodulator (DEMOD) 354,receive processor 356, controller/processor 359, memory 360, and/or thelike) may receive the first collision report(s).

At block 1204, the UE transmits a second collision report indicatingallocation collisions detected by the UE on at least one secondmonitored subset of sidelink resources. For example, the UE (e.g., usingthe antenna 352, modulator (MOD) 354, transmit processor 368,controller/processor 359, memory 360, and/or the like) may transmit thesecond collision report.

Implementation examples are described in the following numbered clauses.

-   -   1. A method of wireless communication by a user equipment (UE),        comprising:        -   receiving at least one first collision report, each first            collision report indicating at least one first monitored            subset of sidelink resources that were monitored by a remote            sidelink UE; and        -   transmitting a second collision report indicating allocation            collisions detected by the UE on at least one second            monitored subset of sidelink resources, each of the at least            one second monitored subset of sidelink resources differing            from each of the at least one first monitored subset of            sidelink resources indicated in the received at least one            first collision report, the second collision report further            comprising an indication of each of the at least one second            monitored subset of sidelink resources.    -   2. The method of clause 1, wherein the at least one second        monitored subset of sidelink resources comprises a second        plurality of frequency subbands and the at least one first        monitored subset of sidelink resources comprises a first        plurality of frequency subbands.    -   3. The method of clause 1 or 2, wherein the at least one second        monitored subset of sidelink resources comprises a second        plurality of subframes and the at least one first monitored        subset of sidelink resources comprises a first plurality of        subframes.    -   4. The method of any the proceeding clauses, wherein sidelink        resources comprise cellular vehicle-to-everything (CV2X)        resources.    -   5. The method of any the proceeding clauses, further comprising        monitoring for and reporting of the detected allocation        collisions in the at least one second monitored subset of        sidelink resources based on the received at least one first        collision report, prior to transmitting the second collision        report.    -   6. The method of any the proceeding clauses, further comprising        reporting a capability for monitoring allocation collisions and        reporting the detected allocation collisions, the capability        corresponding to a quantity of subsets of resources that can be        monitored by the UE.    -   7. The method of any the proceeding clauses, further comprising        preventing transmission of the second collision report in        response to receiving a third collision report indicating at        least a portion of the at least one second monitored subset of        sidelink resources is monitored by another remote sidelink UE.    -   8. The method of any the proceeding clauses, further comprising        selecting at least one third subset of resources for collision        monitoring and reporting that differs from each overlapping        resource of the at least one second monitored subset of sidelink        resources and the at least one first monitored subset of        sidelink resources in response to the preventing transmission of        the second collision report.    -   9. The method of any the proceeding clauses, wherein        transmitting the second collision report is triggered by        detecting one or more allocation collisions on a sidelink        resource of the at least one second monitored subset of sidelink        resources.    -   10. The method of any the proceeding clauses, wherein the second        collision report indicates zero detected allocation collisions        corresponding to the at least one second monitored subset of        sidelink resources.    -   11. The method of any the proceeding clauses, wherein        transmitting the second collision report occurs at least once in        a time period in response to detecting zero allocation        collisions corresponding to the at least one second subset of        sidelink resources, and receiving the at least one first        collision report occurs at least once in the time period.    -   12. The method of any the proceeding clauses, wherein at least        one of the second collision report and each first collision        report indicates the time period.    -   13. The method of any the proceeding clauses, further comprising        receiving at least one third collision report indicating at        least one road side unit (RSU) monitored subset of sidelink        resources that were monitored by an RSU.    -   14. An apparatus for a user equipment (UE) for wireless        communication, comprising:        -   a memory; and        -   at least one processor coupled to the memory, the at least            one processor configured:            -   to receive at least one first collision report, each                first collision report indicating at least one first                monitored subset of sidelink resources that were                monitored by a remote sidelink UE; and            -   to transmit a second collision report indicating                allocation collisions detected by the UE on at least one                second monitored subset of sidelink resources, each of                the at least one second monitored subset of sidelink                resources differing from each of the at least one first                monitored subset of sidelink resources indicated in the                received at least one first collision report, the second                collision report further comprising an indication of                each of the at least one second monitored subset of                sidelink resources.    -   15. The apparatus of clause 14, wherein the at least one second        monitored subset of sidelink resources comprises a second        plurality of frequency subbands and the at least one first        monitored subset of sidelink resources comprises a first        plurality of frequency subbands.    -   16. The apparatus of clause 14 or 15, wherein the at least one        second monitored subset of sidelink resources comprises a second        plurality of subframes and the at least one first monitored        subset of sidelink resources comprises a first plurality of        subframes.    -   17. The apparatus of clause 14, 15, or 16, wherein sidelink        resources comprise cellular vehicle-to-everything (CV2X)        resources.    -   18. The apparatus of any of the clauses 14-17, wherein the at        least one processor is further configured to monitor for and        report the detected allocation collisions in the at least one        second monitored subset of sidelink resources based on the        received at least one first collision report, prior to        transmitting the second collision report.    -   19. The apparatus of any of the clauses 14-18, wherein the at        least one processor is further configured to report a capability        for monitoring allocation collisions and report the detected        allocation collisions, the capability corresponding to a        quantity of subsets of resources that can be monitored by the        UE.    -   20. The apparatus of any of the clauses 14-19, wherein the at        least one processor is further configured to prevent        transmission of the second collision report in response to        receiving a third collision report indicating at least a portion        of the at least one second monitored subset of sidelink        resources is monitored by another remote sidelink UE.    -   21. The apparatus of any of the clauses 14-20, wherein the at        least one processor is further configured to select at least one        third subset of resources for collision monitoring and reporting        that differs from each overlapping resource of the at least one        second monitored subset of sidelink resources and the at least        one first monitored subset of sidelink resources in response to        the preventing transmission of the second collision report.    -   22. The apparatus of any of the clauses 14-21, wherein the at        least one processor is further configured to trigger        transmitting the second collision report in response to        detecting one or more allocation collisions on a sidelink        resource of the at least one second monitored subset of sidelink        resources.    -   23. The apparatus of any of the clauses 14-22, wherein the        second collision report indicates zero detected allocation        collisions corresponding to the at least one second monitored        subset of sidelink resources.    -   24. The apparatus of any of the clauses 14-23, wherein the at        least one processor is further configured to transmit the second        collision report at least once in a time period in response to        detecting zero allocation collisions corresponding to the at        least one second subset of sidelink resources, and to receive        the at least one first collision report at least once in the        time period.    -   25. The apparatus of any of the clauses 14-24, wherein at least        one of the second collision report and each first collision        report indicates the time period.    -   26. The apparatus of any of the clauses 14-25, wherein the at        least one processor is further configured to receive at least        one third collision report indicating at least one road side        unit (RSU) monitored subset of sidelink resources that were        monitored by an RSU.    -   27. An apparatus for a user equipment (UE) for wireless        communication, comprising:        -   means for receiving at least one first collision report,            each first collision report indicating at least one first            monitored subset of sidelink resources that were monitored            by a remote sidelink UE; and        -   means for transmitting a second collision report indicating            allocation collisions detected by the UE on at least one            second monitored subset of sidelink resources, each of the            at least one second monitored subset of sidelink resources            differing from each of the at least one first monitored            subset of sidelink resources indicated in the received at            least one first collision report, the second collision            report further comprising an indication of each of the at            least one second monitored subset of sidelink resources.    -   28. The apparatus of clause 27, wherein sidelink resources        comprise cellular vehicle-to-everything (CV2X) resources.    -   29. The apparatus of clause 27 or 28, further comprising means        for monitoring for and reporting of the detected allocation        collisions in the at least one second monitored subset of        sidelink resources based on the received at least one first        collision report, prior to transmitting the second collision        report.

The foregoing disclosure provides illustration and description, but isnot intended to be exhaustive or to limit the aspects to the preciseform disclosed. Modifications and variations may be made in light of theabove disclosure or may be acquired from practice of the aspects.

As used, the term “component” is intended to be broadly construed ashardware, firmware, and/or a combination of hardware and software. Asused, a processor is implemented in hardware, firmware, and/or acombination of hardware and software.

Some aspects are described in connection with thresholds. As used,satisfying a threshold may, depending on the context, refer to a valuebeing greater than the threshold, greater than or equal to thethreshold, less than the threshold, less than or equal to the threshold,equal to the threshold, not equal to the threshold, and/or the like.

It will be apparent that systems and/or methods described may beimplemented in different forms of hardware, firmware, and/or acombination of hardware and software. The actual specialized controlhardware or software code used to implement these systems and/or methodsis not limiting of the aspects. Thus, the operation and behavior of thesystems and/or methods were described without reference to specificsoftware code—it being understood that software and hardware can bedesigned to implement the systems and/or methods based, at least inpart, on the description.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of various aspects. In fact, many ofthese features may be combined in ways not specifically recited in theclaims and/or disclosed in the specification. Although each dependentclaim listed below may directly depend on only one claim, the disclosureof various aspects includes each dependent claim in combination withevery other claim in the claim set. A phrase referring to “at least oneof” a list of items refers to any combination of those items, includingsingle members. As an example, “at least one of: a, b, or c” is intendedto cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combinationwith multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c,a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering ofa, b, and c).

No element, act, or instruction used should be construed as critical oressential unless explicitly described as such. Also, as used, thearticles “a” and “an” are intended to include one or more items, and maybe used interchangeably with “one or more.” Furthermore, as used, theterms “set” and “group” are intended to include one or more items (e.g.,related items, unrelated items, a combination of related and unrelateditems, and/or the like), and may be used interchangeably with “one ormore.” Where only one item is intended, the phrase “only one” or similarlanguage is used. Also, as used, the terms “has,” “have,” “having,”and/or the like are intended to be open-ended terms. Further, the phrase“based on” is intended to mean “based, at least in part, on” unlessexplicitly stated otherwise.

What is claimed is:
 1. A method of wireless communication by a userequipment (UE), comprising: receiving at least one first collisionreport, each first collision report indicating at least one firstmonitored subset of sidelink resources that were monitored by a remotesidelink UE; and transmitting a second collision report indicatingallocation collisions detected by the UE on at least one secondmonitored subset of sidelink resources, each of the at least one secondmonitored subset of sidelink resources differing from each of the atleast one first monitored subset of sidelink resources indicated in thereceived at least one first collision report, the second collisionreport further comprising an indication of each of the at least onesecond monitored subset of sidelink resources.
 2. The method of claim 1,wherein the at least one second monitored subset of sidelink resourcescomprises a second plurality of frequency subbands and the at least onefirst monitored subset of sidelink resources comprises a first pluralityof frequency subbands.
 3. The method of claim 1, wherein the at leastone second monitored subset of sidelink resources comprises a secondplurality of subframes and the at least one first monitored subset ofsidelink resources comprises a first plurality of subframes.
 4. Themethod of claim 1, wherein sidelink resources comprise cellularvehicle-to-everything (CV2X) resources.
 5. The method of claim 1,further comprising monitoring for and reporting of the detectedallocation collisions in the at least one second monitored subset ofsidelink resources based on the received at least one first collisionreport, prior to transmitting the second collision report.
 6. The methodof claim 1, further comprising reporting a capability for monitoringallocation collisions and reporting the detected allocation collisions,the capability corresponding to a quantity of subsets of resources thatcan be monitored by the UE.
 7. The method of claim 1, further comprisingpreventing transmission of the second collision report in response toreceiving a third collision report indicating at least a portion of theat least one second monitored subset of sidelink resources is monitoredby another remote sidelink UE.
 8. The method of claim 7, furthercomprising selecting at least one third subset of resources forcollision monitoring and reporting that differs from each overlappingresource of the at least one second monitored subset of sidelinkresources and the at least one first monitored subset of sidelinkresources in response to the preventing transmission of the secondcollision report.
 9. The method of claim 1, wherein transmitting thesecond collision report is triggered by detecting one or more allocationcollisions on a sidelink resource of the at least one second monitoredsubset of sidelink resources.
 10. The method of claim 1, wherein thesecond collision report indicates zero detected allocation collisionscorresponding to the at least one second monitored subset of sidelinkresources.
 11. The method of claim 10, wherein transmitting the secondcollision report occurs at least once in a time period in response todetecting zero allocation collisions corresponding to the at least onesecond subset of sidelink resources, and receiving the at least onefirst collision report occurs at least once in the time period.
 12. Themethod of claim 11, wherein at least one of the second collision reportand each first collision report indicates the time period.
 13. Themethod of claim 1, further comprising receiving at least one thirdcollision report indicating at least one road side unit (RSU) monitoredsubset of sidelink resources that were monitored by an RSU.
 14. Anapparatus for a user equipment (UE) for wireless communication,comprising: a memory; and at least one processor coupled to the memory,the at least one processor configured: to receive at least one firstcollision report, each first collision report indicating at least onefirst monitored subset of sidelink resources that were monitored by aremote sidelink UE; and to transmit a second collision report indicatingallocation collisions detected by the UE on at least one secondmonitored subset of sidelink resources, each of the at least one secondmonitored subset of sidelink resources differing from each of the atleast one first monitored subset of sidelink resources indicated in thereceived at least one first collision report, the second collisionreport further comprising an indication of each of the at least onesecond monitored subset of sidelink resources.
 15. The apparatus ofclaim 14, wherein the at least one second monitored subset of sidelinkresources comprises a second plurality of frequency subbands and the atleast one first monitored subset of sidelink resources comprises a firstplurality of frequency subbands.
 16. The apparatus of claim 14, whereinthe at least one second monitored subset of sidelink resources comprisesa second plurality of subframes and the at least one first monitoredsubset of sidelink resources comprises a first plurality of subframes.17. The apparatus of claim 14, wherein sidelink resources comprisecellular vehicle-to-everything (CV2X) resources.
 18. The apparatus ofclaim 14, wherein the at least one processor is further configured tomonitor for and report the detected allocation collisions in the atleast one second monitored subset of sidelink resources based on thereceived at least one first collision report, prior to transmitting thesecond collision report.
 19. The apparatus of claim 14, wherein the atleast one processor is further configured to report a capability formonitoring allocation collisions and report the detected allocationcollisions, the capability corresponding to a quantity of subsets ofresources that can be monitored by the UE.
 20. The apparatus of claim14, wherein the at least one processor is further configured to preventtransmission of the second collision report in response to receiving athird collision report indicating at least a portion of the at least onesecond monitored subset of sidelink resources is monitored by anotherremote sidelink UE.
 21. The apparatus of claim 20, wherein the at leastone processor is further configured to select at least one third subsetof resources for collision monitoring and reporting that differs fromeach overlapping resource of the at least one second monitored subset ofsidelink resources and the at least one first monitored subset ofsidelink resources in response to the preventing transmission of thesecond collision report.
 22. The apparatus of claim 14, wherein the atleast one processor is further configured to trigger transmitting thesecond collision report in response to detecting one or more allocationcollisions on a sidelink resource of the at least one second monitoredsubset of sidelink resources.
 23. The apparatus of claim 14, wherein thesecond collision report indicates zero detected allocation collisionscorresponding to the at least one second monitored subset of sidelinkresources.
 24. The apparatus of claim 23, wherein the at least oneprocessor is further configured to transmit the second collision reportat least once in a time period in response to detecting zero allocationcollisions corresponding to the at least one second subset of sidelinkresources.
 25. The apparatus of claim 24, wherein the second collisionreport indicates the time period.
 26. The apparatus of claim 14, whereinthe at least one processor is further configured to receive at least onethird collision report indicating at least one road side unit (RSU)monitored subset of sidelink resources that were monitored by an RSU.27. An apparatus for a user equipment (UE) for wireless communication,comprising: means for receiving at least one first collision report,each first collision report indicating at least one first monitoredsubset of sidelink resources that were monitored by a remote sidelinkUE; and means for transmitting a second collision report indicatingallocation collisions detected by the UE on at least one secondmonitored subset of sidelink resources, each of the at least one secondmonitored subset of sidelink resources differing from each of the atleast one first monitored subset of sidelink resources indicated in thereceived at least one first collision report, the second collisionreport further comprising an indication of each of the at least onesecond monitored subset of sidelink resources.
 28. The apparatus ofclaim 27, wherein sidelink resources comprise cellularvehicle-to-everything (CV2X) resources.
 29. The apparatus of claim 27,further comprising means for monitoring for and reporting of thedetected allocation collisions in the at least one second monitoredsubset of sidelink resources based on the received at least one firstcollision report, prior to transmitting the second collision report. 30.A non-transitory computer-readable medium having program code recordedthereon, the program code executed by a processor of a user equipment(UE) and comprising: program code to receive at least one firstcollision report, each first collision report indicating at least onefirst monitored subset of sidelink resources that were monitored by aremote sidelink UE; and program code to transmit a second collisionreport indicating allocation collisions detected by the UE on at leastone second monitored subset of sidelink resources, each of the at leastone second monitored subset of sidelink resources differing from each ofthe at least one first monitored subset of sidelink resources indicatedin the received at least one first collision report, the secondcollision report further comprising an indication of each of the atleast one second monitored subset of sidelink resources.